For those that don't know much about this stuff, there are a few ways you can edit this information.
The way I would do it, is to use vim ( my personal preference ). To get to this on your mac you can type in the terminal:
vim ~/.bashrc or
vim ~/.profile and add the lines in there -- vim can be tricky though if you've never used it.
The other, much easier, way is to use textedit. With the same files as before, you would type this command in the terminal:
open -a TextEdit ~/.bashrc or
open -a TextEdit ~/.profile
NOTE: if you're like me, you don't use bash. I use Oh My ZSH and as such I would use .zshrc instead of .bashrc
Mine is in .profile and haven't had any issues. My full profile looks like this:
export PATH="$PATH:$HOME/.rvm/bin" # Add RVM to PATH for scripting
[ [-s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm" # Load RVM into a shell session *as a function*